This is certainly a shock for Vietnam, but it is not unexpected. Though the kidnapping and beheading of Western hostages in front of the black flag of the Islamic State tends to garner international media attention, regional mariners have been the Abu Sayyaf’s main target since early 2016. This has important implications for Vietnam and it could also be an important opening should they decide to play a greater role in regional security.

To date, the Abu Sayyaf have executed three Vietnamese sailors and killed one more during shipboarding. They boarded two Vietnamese vessels, the first on 11 November 2016 and the second on 20 February 2017. 12 Vietnamese nationals have been taken hostage. One escaped his captors. 10 additional Vietnamese sailors were not taken hostage, but very well could have been had the Abu Sayyaf had more or larger speed boats.

The Vietnamese are not alone. Since March of 2016, the Abu Sayyaf have shifted the majority of their kidnap for ransom operations to the high seas. Between March 2016 and July 2017, the Abu Sayyaf boarded 17 ships and taken some 65 hostages from six countries, including Vietnam. In all 30 have been released, usually after a ransom was paid, seven escaped their captors, three were rescued by Philippine security forces, and four were executed. Two others were killed during the attacks, while eight seamen escaped during the shipjackings. An additional 40 seamen were not taken hostage.

The Abu Sayyaf have shifted their hostage taking to sailors and fishermen for several reasons. First, trawlers and tug-boats pulling coal barges through the waters between Malaysia, Indonesia, and the Philippines, are slow moving and easy to board. But even still, the ASG, on their fast patrol craft, have now boarded three larger ocean going vessels, including two Vietnamese-flagged ships, and unsuccessfully attempted to board two Japanese-flagged vessels.

Second, the shipping and large fishing concerns have tended to pay the ransoms. Governments of course deny this, saying that they do not “negotiate with terrorists”, for fear that this would only incentivize hostage taking. But families, corporations, insurance companies, do not have to think about those implications. Their responsibility is to save loved ones or personnel.

Third, the waters that the Abu Sayyaf hunt in are large and contested. While Indonesia and the Philippines recently demarcated their maritime boundary, there is no agreed upon maritime boundary between the Philippines and Malaysia (owing to the dispute over Sabah), and between Malaysia and Indonesia.

Fourth, the maritime policing capabilities of Indonesia and the Philippines are weak; though stronger in Malaysia. In early July, the three states began coordinated maritime patrols. That was followed by a Malaysian Minister of Defense announcement that coordinated aerial surveillance patrols would soon be underway. With the siege of Marawi City by pro-Islamic State militants, including foreign fighters, now in its third month, controlling the maritime domain is all the more important.

What does this mean for Vietnam? The Philippine government is beset by a number of complex and interconnected insurgencies that it is not going to defeat militarily. It has neither the resources nor the will to resolve the situation in Mindanao. As such, the kidnappings will continue. The number of Vietnamese-flagged ocean-going vessels is growing rapidly. So is the number of nationals serving as seamen on foreign flagged ships. While Vietnam focuses its attention on trade with major partners, such as the United States, the European Union, and Japan, it cannot afford to neglect intra-ASEAN trade. Together, these mean that Vietnamese sailors will increasingly be at risk.

So what should the Vietnamese government do? Immediately after such killings, there is pressure on the government to pay the ransom to secure the release of the remaining eight sailors. The government has banned Vietnamese state media from covering the issue, an indication of the sensitivity of the issue, and citing ongoing negotiations. The government should resist the temptation to pay the ransom, though I would understand if the families or shipping companies did. Hanoi’s diplomats should work with the Philippine government and security forces to secure their release.

But the attack has also created an opportunity should Vietnam want to play a greater role in regional security.

Vietnam has made impressive investments in its Navy and Coast Guard. The country has plenty of water to defend and outstanding territorial disputes in the Spratly and Parcel Islands. Defending its maritime claims is their primary responsibility.

But the Vietnamese Navy and Coast Guard should now consider sending a vessel on a routine basis to help its Philippine, Malaysian, and Indonesian partners patrol the waters in the Sulu Sea. Singapore has already shown an interest in assisting. This would help in developing interoperability, confidence, and experience in working besides their counterparts. Whereas maritime cooperation is harder in the South China Sea, where territorial disputes with Malaysia and the Philippines remain, sovereignty is not at stake with counter-piracy and counter-terrorism operations. And such an operation is unlikely to incur China’s wrath.

Yes, there is a cost to this. Vietnam has limited resources. But whether it admits it or not, Vietnam has an interest in Philippine security. And even the small multilateral presence seems to have had an effect: ship-boardings are down.

More importantly, if Vietnam wants to help build up a rules-based order and contribute to maritime and regional security, this is a great and low cost way to do it. Helping to secure sea lanes of communication is important to Vietnam’s economic prosperity. A more robust maritime presence in the Sulu Sea has helped slow the number of attacks. Gaining multilateral experience will improve the professionalism of its Navy and Coast Guard. And it will sow the seeds of future multilateral maritime security cooperation that Vietnamese security ultimately depends on.

Zachary Abuza, PhD, is a Professor at the National War College. The views expressed here are his own, and not the views of the Department of Defense or National War College.